Apparatus for treating venous insufficiency

ABSTRACT

A catheter delivers an electrode within a vein for a minimally invasive treatment of varicose veins and venous insufficiency using RF energy. The catheter is introduced into a patient and positioned within the section of the vein to be treated. The electrode radiates high frequency energy towards the vein, and the surrounding venous tissue becomes heated and begins to shrink. The catheter includes a controllable member for limiting the amount of shrinkage of the vein to the diameter of the member. The electrode remains active until there has been sufficient shrinkage of the vein. The extent of shrinkage of the vein may be detected by fluoroscopy. After treating one section of the vein, the catheter and the electrode can be repositioned intraluminally within the vein to treat different sections of the vein until all desired venous sections and valves are repaired and rendered functionally competent.

This is a continuation of U.S. patent application Ser. No. 09/495,667,filed Feb. 1, 2000, now U.S. Pat. No. 6,613,045; which is a continuationof U.S. patent application Ser. No. 08/610,911, filed Mar. 5, 1996, nowU.S. Pat No. 6,036,687.

BACKGROUND OF THE INVENTION

This invention relates to the treatment and correction of venousinsufficiency or varicose veins, and more particularly to a minimallyinvasive procedure using a catheter-based system to deploy an electrodefor providing radio frequency (RF) energy, microwave energy, or thermalenergy to shrink a vein intraluminally to change the fluid flow dynamicsand to restore the competency of the venous valve and the properfunction of the vein.

The human venous system of the lower limb consists essentially of thesuperficial venous system and the deep venous system with perforatingveins connecting the two systems. The superficial system includes thelong or great saphenous vein and the short saphenous vein. The deepvenous system includes the anterior and posterior tibial veins whichunite to form the popliteal vein, which in turn becomes the femoral veinwhen joined by the short saphenous vein.

The venous systems contain numerous one-way valves for directing bloodflow back to the heart. Venous valves are usually bicuspid valves, witheach cusp forming a sack or reservoir for blood which, under pressure,forces the free surfaces of the cusps together to prevent retrogradeflow of the blood and allow antegrade flow to the heart. When anincompetent valve is in the flow path of retrograde flow toward thefoot, the valve is unable to close because the cusps do not form aproper seal and retrograde flow of blood cannot be stopped.

Incompetence in the venous system can result from vein dilation, whichcauses the veins to swell with additional blood. Separation of the cuspsof the venous valve at the commissure may occur as a result. Theleaflets are stretched by the dilation of the vein and concomitantincrease in the vein diameter which the leaflets traverse. Stretching ofthe leaflets of the venous valve results in redundancy which allows theleaflets to fold on themselves and leave the valve open. This is calledprolapse, which can allow reflux of blood in the vein. Eventually thevenous valve fails, thereby increasing the strain and pressure on thelower venous sections and overlying tissues. Two venous diseases whichoften involve vein dilation are varicose veins and chronic venousinsufficiency.

The varicose vein condition includes dilatation and tortuosity of thesuperficial veins of the lower limb, resulting in unsightlydiscoloration, pain and ulceration. Varicose veins often involveincompetence of one or more venous valves, which allow reflux of bloodfrom the deep venous system to the superficial venous system or refluxwithin the superficial system. Current treatments include such invasiveopen surgical procedures as vein stripping, sclerotherapy, andoccasionally, vein grafting, venous valvuloplasty, and the implantationof various prosthetic devices. The removal of varicose veins from thebody can be a tedious, time-consuming procedure having a painful andslow healing process. Complications, scarring, and the loss of the veinfor future cardiac and other by-pass procedures may also result. Alongwith the complications and risks of invasive open surgery, varicoseveins may persist or reoccur, particularly when the valvular problem isnot corrected. Due to the long, arduous, and tedious nature of thesurgical procedure, treating multiple venous sections can exceed thephysical stamina of the physician, and thus render complete treatment ofthe varicose vein conditions impractical.

Chronic venous insufficiency (CVI) is a problem caused by hydrodynamicforces acting on the tissues of the body, especially the legs, anklesand feet. As the veins dilate due to increased pressure, the valves inthe veins fail. This causes the pressure to increase on the next valveand vein segment down, causing those veins to dilate, and as thiscontinues, the valves in the veins eventually all fail. As they fail,the effective height of the column of blood above the feet and anklesgrows, and the weight and hydrostatic pressure exerted on the tissues ofthe ankle and foot increases. When the weight of that column reaches acritical point from the valve failures, ulcerations of the ankle beginto form, which start deep and eventually come to the surface. Theseulcerations do not heal easily because the weight of blood which causedthem continues to persist, and have the tendency to enlarge the ulcer.

Chronic venous insufficiency often consists of hypertension of the lowerlimb in the deep, perforating and often superficial veins, and mayresult in discoloration, pain, swelling and ulceration. Existingtreatments for chronic venous insufficiency are often less than ideal.These treatments include the elevation of the legs, compressing theveins externally with elastic support hose, and surgical repair bygrafting vein sections with healthy valves from the arm into the leg.These methods have variable effectiveness. Moreover, invasive surgeryhas its associated complications with risk to life and expense.Similarly, the palliative therapies require major lifestyle changes forthe patient. For example, the ulcers will reoccur unless the patientcontinues to elevate the legs and use support hose continuouslythroughout the life of the patient.

Due to the time-consuming and invasive nature of the current surgicaltreatments, such as vein grafting, typically only one valve is treatedduring any single procedure. This greatly limits the ability of thephysician to fully treat patients suffering from chronic venousinsufficiency. Every instance of invasive surgery, however, has itsassociated complications with risk to life and expense.

The ligation of vascular lumen by tying a suture around them,cauterization or coagulation using electrical energy from an electrodehas been employed as an alternative to stripping, or the surgicalremoval of such veins. However, ligation procedures close off the lumen,essentially destroying their functional capability. For example, it isknown to introduce an electrode into the leg of a patient, and positionthe electrode adjacent to the exterior of the varicose veins to betreated. Through a small stab incision, a probe is forced through thesubcutaneous layer between the fascia and the skin, and then to thevarious veins to be destroyed. Electrodes at the outer end of the probeare placed adjacent to the varicose veins. Once properly positioned, analternating current of 500 kilohertz is applied to destroy the adjacentvaricose veins by fulguration. The fulgurated veins lose the function ofallowing blood to flow through, and are no longer of use. For example,ligating the saphenous vein would render that vein unavailable forharvesting in other surgical procedures such as coronary by-passoperations. Ligation techniques which functionally destroy the veinlumen would appear to be inappropriate to a corrective procedure forrestoring and maintaining the function of the vein.

A need exists in the art to treat dilated veins, such as those resultingin varicose veins or from venous insufficiency, which maintains thepatency of the veins for venous function and yet restores valvularcompetency.

SUMMARY OF THE INVENTION

Briefly, and in general terms, the present invention provides a lessinvasive and faster method for solving the underlying problems ofvaricose veins and venous insufficiency, and uses a novel repair system,including a catheter for placement of an electrode for delivering radiofrequency energy. The present invention includes a method of applyingenergy to cause shrinkage of a vein, the method comprising the steps ofintroducing a catheter having a working end and means for heatinglocated at the working end, to a treatment site in a vein; positioningthe means for heating at the treatment site in the vein; applying energyfrom the means for heating to controllably heat the treatment site andcause shrinkage of the vein; and terminating the emission of energy fromthe means for heating after sufficient shrinkage of the vein hasoccurred so as to restore valvular competency or so that the veinremains patent so as to continue to function as a blood conduit.

The method of the present invention is a minimally invasive procedurewhich eliminates the need for open surgical procedures for venousrepair, including venous valvuloplasty, and the transplantation of anarm vein into the leg.

An apparatus for performing the method of applying radiant energy tocause shrinkage of a vein, comprises a catheter having a working end,means for heating a venous treatment area to cause shrinkage of thevein, wherein the means for heating is located at the working end of thecatheter, and means for preventing further shrinkage after sufficientshrinkage of the vein, so that the vein continues to function. Theheating means may include RF electrodes to heat and shrink the vein.Balloons, or other mechanisms for controlling the outer diameter of theheating means, may be used to limit the amount of shrinkage. Feedbackcontrol systems may be applied to these mechanisms, or may be used tocontrol the application of energy to heat the venous tissue, in order tocontrol the amount of shrinkage.

Features of the present invention include restoring the competence ofvenous valves, normalizing flow patterns, dynamics, and pressure, andreducing sections of dilated varicose veins to a normal diameter forcosmetic purposes. The treated veins remain patent and can continue tofunction and return blood to the heart.

One feature of the present invention is to provide a procedure forrestoring venous valvular competency by controllably shrinking theotherwise dilated lumen of the vein to a desired diameter.

Another feature of the present invention is to control or adjust theeffective diameter of the catheter or electrode configuration in orderto control the amount of circumferential shrinking experienced by thevein wall. An extendable member located adjacent to the working end ofthe catheter can increase the effective diameter of the catheter andlimit the shrinkage of the vein.

Another feature of the present invention is to provide a catheterelectrode which generates a radio frequency field around thecircumference of the catheter in order to shrink the vein wallcircumferentially and omnidirectionally while minimizing lengthwisecontraction when the catheter electrode is positioned intraluminallywithin the vein.

Yet another feature of the present invention is to generate a field at aspecific frequency around the catheter in order to minimize coagulationwithin the vein, and to control the spread of heating within the venoustissue.

An additional feature of the present invention is to protect the venousvalve leaflets by minimizing the heating effect on the venous valves bythe selective positioning of the electrodes within the vein.

Another feature of the present invention is to deliver cooling fluid tothe bloodstream in order reduce the likelihood of heating the blood to apoint of coagulation.

An additional feature of the present invention is to prevent shrinkageof the vein past the end of the catheter.

Another feature of the present invention is to maintain the electrodesin apposition to the venous tissue to ensure that the heat is deliveredtowards the venous tissue, and not the blood moving through the vein.

Another feature of the present invention is to use electrodes which arebowable members that can be deflected radially outward for maintainingcontact with the venous tissue. The bowable members are conductivelongitudinal electrodes substantially covered by an insulating film,except for the portion which is to come into apposition with the venoustissue.

Another feature of the present invention is a balloon located on oneside of the catheter having electrodes on the opposite side. Inflationof the balloon will move the electrodes into apposition with the veinwall on the opposite side.

Yet another feature of the present invention is to provide a procedurewhich can treat multiple venous sites quickly and easily.

An additional feature of the present invention is that no foreign objector prothesis remain in the vasculature after treatment.

These and other aspects and advantages of the present invention willbecome apparent from the following more detailed description, when takenin conjunction with the accompanying drawings which illustrate, by wayof example, the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cross-sectional view of a dilated vein having incompetentvenous valves in a lower limb which are to be treated in accordance withthe present invention;

FIG. 2 shows a representative view of a venous section from FIG. 1 takenalong lines 2-2 which is to be treated in accordance with the presentinvention;

FIG. 3 shows a partial cross-sectional view of a catheter havingelectrodes being delivered antegrade to a venous treatment site inaccordance with the present invention;

FIG. 4 shows the partial cross-sectional view of the venous section ofFIG. 2 after being treated in accordance with the present invention;

FIG. 5 shows a partial cross-sectional view of the catheter and veinshown in FIG. 3 being delivered to another venous treatment site inaccordance with the present invention;

FIG. 6 shows a partial cross-sectional view of a catheter beingdelivered retrograde and deflected laterally to a venous treatment sitein accordance with the present invention;

FIG. 7 shows a partial cross-sectional view of an embodiment of thecatheter having a bulbous tip and ring electrodes for treating a dilatedvein in accordance with the present invention;

FIG. 8 shows a partial cross-sectional view of an embodiment of thecatheter having a flush tip at the working end and ring electrodes fortreating a dilated vein in accordance with the present invention;

FIG. 9 shows a partial cross-sectional view of an embodiment of thecatheter having a cap electrode for treating a dilated vein inaccordance with the present invention;

FIG. 10 shows a partial cross-sectional view of another embodiment ofthe catheter having a cap electrode and a balloon to center theplacement of the electrode within the vein to be treated;

FIGS. 11 a, 11 b, and 11 c show partial cross-sectional views of anotherembodiment of the catheter having a bendable tip which deflectslaterally for causing apposition between the electrodes of the catheterand the vein wall in accordance with the invention;

FIGS. 12 a and 12 b show partial cross-sectional side and top views,respectively, of another embodiment of the catheter having a balloon onone side of the catheter and longitudinal electrodes on the other sideat the working end of the catheter for moving the electrodes intoappositional contact with the vein wall in accordance with theinvention;

FIG. 13 shows another embodiment of the catheter having bendableelectrodes which deflect outwardly for increasing the effective diameterat the working end of the catheter in accordance with the invention;

FIG. 14 shows another embodiment of the catheter having a balloon andbendable members with electrodes which deflect outwardly for increasingthe effective diameter at the working end of the catheter in accordancewith the invention;

FIG. 15 a shows a cross-sectional view of an embodiment of the cathetershown in FIG. 14 having four equidistantly spaced electrodes inaccordance with the present invention;

FIG. 15 b shows a cross-sectional view of an embodiment of the cathetershown in FIG. 14 having four electrodes preferentially spaced to formtwo pairs of electrodes in accordance with the present invention;

FIG. 16 shows a partial cross-sectional view of another embodiment ofthe catheter having four equidistantly spaced electrodes, and beingdelivered retrograde to a venous treatment site in accordance with thepresent invention;

FIG. 17 shows a partial cross-sectional view of an embodiment of anover-the-wire balloon catheter having four equidistantly spaced apartelectrodes on the surface of the balloon in accordance with the presentinvention;

FIG. 18 shows a cross-sectional view-taken along the lines 18-18 of theover-the-wire balloon catheter of FIG. 17 in accordance with the presentinvention;

FIG. 19 shows a partial cross-sectional view of another embodiment ofthe catheter having electrodes located within the balloon portion inaccordance with the present invention;

FIG. 20 shows a lengthwise cross-sectional view of another embodiment ofthe catheter having a conical wedge member for moving the electrodes atthe working end of the catheter into apposition with the venous tissuein accordance with the present invention;

FIG. 21 shows a cross-sectional view taken along lines 21-21 in FIG. 20in accordance with the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

As shown in the exemplary drawings, the invention is directed toward theintravenous treatment of veins using a catheter to deliver at least oneelectrode to a venous treatment site. As used herein, like referencenumerals will designate similar elements in the various embodiments ofthe present invention to be discussed. In addition, unless otherwisenoted, the term working end will refer to the direction toward thetreatment site in the patient, and the term connecting end will refer tothe direction away from the treatment site in the patient. The inventionwill be described in relation to the treatment of the venous system ofthe lower limbs. It is to be understood, however, that the invention isnot limited thereto and may be employed intraluminally to treat veins inother areas of the body such as hemorrhoids, esophageal varices, andvenous-drainage-impotence of the penis. Furthermore, although theinvention will be described as using RF energy from the electrode, it isto be understood that other forms of energy such as microwaves,ultrasound, direct current, circulating heated fluid, radiant light, andlasers can be used, and that the thermal energy generated from aresistive coil or curie point element may be used as well.

A partial cross-sectional view of a dilated vein from a lower limbhaving incompetent valves is shown in FIG. 1. These veins are oftendisposed within muscle tissue. Veins have bicuspid valves, and in anormal and competent valve, each cusp forms a sack or reservoir forblood which, under pressure, forces the free edges of the cusps togetherto prevent retrograde flow of the blood and allow only antegrade flow tothe heart. The arrow leading out the top of the vein represents theantegrade flow of blood back to the heart. The venous valves preventretrograde flow as blood is pushed forward through the vein lumen andback to the heart.

When an incompetent valve encounters retrograde flow, the valve isunable to close, the cusps do not seal properly and retrograde flow ofblood may occur. Incompetent valves may result from the stretching ofdilated veins. As the valves fail, increased pressure is imposed on thelower veins and the lower valves of the vein, which in turn exacerbatesthe failure of these lower valves. A cross-sectional perspective view ofa dilated vein taken along lines 2-2 of FIG. 1 is illustrated in FIG. 2.The valve cusps can experience some separation at the commissure due tothe thinning and stretching of the vein wall at the cusps.

The method of the present invention for the minimally invasive treatmentof venous insufficiency can be performed using a catheter 10 to deliverelectrodes 12 to a venous treatment site in order to restore thecompetency of a vein. One embodiment of the catheter 10 for deliveringthe electrodes 12 to the venous treatment site is shown in FIG. 3. Theelectrodes 12 may be two RF ring electrodes 14 and 16 located at theworking end 11 of the catheter 10. This and other embodiments of thecatheter 10 will be described in greater detail later. Further, themethod is contemplated to be used with any suitable appliance forapplying radiant energy, thermal energy, or other forms of energy toheat and shrink the venous tissue in the repair or reconfiguration ofincompetent veins in order to restore venous function or valvularcompetency. Particular discussion will be directed to the treatment ofincompetent and varicose veins in the legs, although the method of thepresent invention is well suited to treating veins in other areas of thebody.

When treating the veins of the lower limbs, the patient is typicallyplaced onto a procedure table with the feet dependent in order to fillthe veins of the leg. The leg of the patient is prepped with antisepticsolution. A percutaneous introducer is inserted into the vein using thewell-known Seldinger technique to access the saphenous or deep veinsystem. Alternatively, a venous cut-down can be used to access the veinsystem to be treated. The procedure for the repair of incompetent veinscan be accomplished by a qualified physician with or withoutfluoroscopic or ultrasonic observation, or under direct visualization.Further, the physician could palpate the treatment area to determine thelocation of the catheter, and the treatment site, during the procedurewhen treating the superficial venous system.

The catheter 10 could be passed within the vein after insertion throughthe introducer, and advanced through to the venous treatment site.Alternatively, a guide wire for the catheter may be inserted into thevein. The wire is advanced antegrade to the venous treatment site, suchas the level of the most proximal incompetent vein site which is to berepaired. The catheter is then inserted upon the wire and is fed up theleg through the vein to the level of the venous section where retrogradeflow exists. In either case, the catheter 10 delivers the electrodes 12to the venous treatment site. Fluoroscopy, x-ray, ultrasound, or asimilar imaging technique could then be used to direct the specificplacement of the catheter and confirmation of position within the vein.X-ray contrast material can be injected through or around the catheterto identify the incompetent venous sections to be repaired.

From the antegrade approach, the catheter can be pushed through thevenous valve so that the electrodes are positioned across the valve ofthe incompetent venous section to be treated. The catheter 10 travelsantegrade through the venous valves, as shown in FIG. 3, and ispositioned so that the electrodes 12 are near a dilated section of thevein to be treated. The electrodes may be positioned so as to extendpast the incompetent venous valve. When the electrodes 12 of thecatheter 10 are positioned at the venous treatment site, the RFgenerator is activated to provide suitable RF energy, preferably at aselected frequency from a range of 250 kHz to 350 MHZ. One suitablefrequency is 40 Mhz. One criteria for the selection of the appliedfrequency is the minimization of coagulation in the vein. Anothercriteria is to control the spread and depth of the thermal effect in thetissue. The extent of heating or depth of penetration into the tissuegenerally increases with lower frequencies, and decreases as thefrequency increases. A microprocessor can be used to select a frequencyfor treating different veins according to the above criteria. Forexample, the microprocessor can include a table stored in memory forassociating specific frequencies for treating various veins and veindiameters according to the criteria of minimizing coagulation andcontrolling the spread or depth of the heating effect. The energyemitted from the electrodes is converted within the venous tissue intoheat. As the temperature of the venous tissue increases, the venoustissue begins to shrink. The shrinkage is due in part to dehydration andthe structural transfiguration of the collagen fibers in the vein.Although the collagen becomes compacted during this process, thecollagen still retains some elasticity. When RF energy is applied nearthe locus of the dilated vein and venous valve, shrinkage of the veincan restore valvular competency by reducing the dilation which ispreventing the proper functioning of the venous valve.

The working end 11 of the catheter 10 near the electrodes 12 physicallylimits the amount of shrinkage. The working end 11 is preferablysufficiently sized or enlarged to prevent the complete ligation of thevein. Other schemes, such as an inflatable balloon, may be used tomechanically limit or control the amount of shrinkage in the vein.

Vein dilation is reduced after RF energy applied from the electrodes 12heats the surrounding venous tissue to cause shrinkage. RF energy is nolonger applied after there has been sufficient shrinkage of the vein toalleviate the dilation of the vein near the valves, so as to restorevenous function or valvular competency. Sufficient shrinkage may bedetected by fluoroscopy, external ultrasound scanning, intravascularultrasound scanning, impedance monitoring, temperature monitoring,direct visualization using an angioscope, or any other suitable method.For example, the catheter 10 can be configured to deliver x-ray contrastmedium to allow visualization by fluoroscopy for assessing the conditionof the vein and the relationship of the catheter to the treatment areaof the vein during the shrinkage process. As an alternative tofluoroscopy, external ultrasound techniques such as B-scanning usingdistinct ultrasound signals from different angles, or intravascularultrasound can be used to acquire a more multidimensional view of thevein shrinkage at the treatment site, which improves the detection ofuneven shrinkage in the vein. An angioscope may also be used to directlyvisualize and determine the extent and degree of vein shrinkage.

After treatment, the commissure and the cusps of the venous valvesshould be closer together with little separation or prolapse, whichindicates a restoration of the competency of the valve. Across-sectional view of the venous valve after being treated with RFenergy is shown in FIG. 4. Valvular competence may be determined bycontrast injection or Doppler probe measurement.

Substantial shrinkage may be achieved very rapidly, depending upon thespecific treatment conditions. Because the shrinkage can proceed at arather rapid rate, the RF energy is preferably applied at low powerlevels. As previously discussed, the frequency of the RF energy isselected to minimize coagulation and to control the spread of theheating effect at the treatment site. The properties of the treatmentsite, such as temperature, can be monitored to provide feedback controlfor the RF energy in order to minimize coagulation. Other techniquessuch as impedance monitoring, and ultrasonic pulse echoing, can beutilized in an automated system which shuts down the application of RFenergy from the electrodes to the venous section when sufficientshrinkage of the vein is detected and to avoid overheating orcauterization of the vein. Monitoring these values in an automaticfeedback control system for the RF energy can also be used to controlthe spread, including the depth, of the heating effect. In allinstances, the application of RF energy is controlled so as to shrinkthe venous tissue sufficiently to restore and maintain the competency ofthe venous valve.

After treating the venous section shown in FIG. 3, the catheter 10 ismoved to the next lower venous valve suffering from insufficiency asshown in FIG. 5. The electrode 12 may be placed across the venous valveas discussed previously in connection with FIG. 3. However, analternative placement of the electrode 12 may be used. For example, asshown in FIG. 5, the electrode 12 is positioned just below or retrogradeto the cusps of the venous valve. Placement of the electrode below thevalve when applying RF energy can be advantageous in minimizing theeffect of localized RF heating on the thin cusps of the venous valvewhile still achieving shrinkage of the vein to restore venous functionor valve competency.

Where the catheter is designed with a fluid delivery lumen, a coolingfluid can be delivered through the delivery lumen to the bloodstreamduring RF heating of the vein being treated. The delivered cooling fluidminimizes any heating effect on the blood, and reduces the risk ofheating the blood to the point of coagulation. The fluid may bedelivered through ports formed along the side of the catheter near theworking end and the electrodes.

While the method has thus far been described as restoring valvularcompetency, the invention is not so limited. A contiguous axial sectionof dilated vein can be treated by applying RF energy along the dilatedvenous section, even if the section is extensive. The dilated vein isshrunk and reduced to a normal diameter under the controlled applicationof RF energy in accordance with the present invention. Such treatmentcan be used in the cosmetic treatment of varicose veins. Further,thickening of the vein may occur during treatment, which can reduce thelikelihood of the recurrence of varicose veins and venous insufficiency.

The catheter 10 can be repositioned to treat as many venous sections andvalves as necessary. RF energy is applied to each venous section to berepaired, until all of the desired venous sections are repaired and thevalves are rendered competent. Multiple incompetent valves andinsufficient or dilated venous sections may be treated and repaired in asingle minimally invasive procedure. If desired, a second introducer canbe inserted into the limb of a patient in order to access either thedeep or the superficial vein system, whichever has yet to be treated.The catheter can then be used to treat incompetent venous sections inthe other vein system.

Instead of the antegrade approach, as shown in FIGS. 3 and 5, thecatheter can deliver the electrodes to the venous treatment site from aretrograde direction. The catheter 10 is introduced through the skin andinto the vein in a retrograde direction. The catheter 10 can penetratethe vein above and adjacent to the incompetent venous section to betreated. The electrodes are advanced until contact with the cusp of thevenous valve is observed by fluoroscopy, ultrasound, or other detectionmethod. The catheter is then pulled back slightly to allow treatment ofthe dilated section of vein. The electrodes are activated to deliver RFenergy to the venous tissue and shrink the vein. The shrinkage of thevein can be limited to prevent ligation and allow the continued functionof the vein. The outer diameter of the catheter or an extendable membercan be controlled to limit the magnitude of the vein shrinkage.

More specific application of the RF energy to the separating commissuresof venous valves can be effective in restoring venous function andvalvular competency. The catheter 10 can be configured to position theelectrodes within the vein and to appose the electrodes with the venoussection to be repaired. The catheter is capable of being deflected,torqued, or otherwise moved to allow for proper placement of theelectrode. Alternatively, a permanent bend may be formed near theworking end of the catheter, which can then be turned and twisted inorder to achieve the desired apposition. Manipulating the working end ofthe catheter enables preferential heating along the vein wall beingtreated, if desired, where the electrodes are placed closer to one sideof the vein wall.

The electrodes 12 on a deflected catheter, as shown in FIG. 6, can beplaced in close apposition to the vein walls near the commissure from aretrograde approach. The catheter may also be manipulated to place theelectrodes in close apposition to the commissures of the venous valve tocause local shrinkage near the commissures to remedy any separation ofthe commissures from vein dilation and to restore venous function andvalvular competency. After treating one end of the valvular commissure,the catheter may then be moved to place the electrodes near thecommissure at the opposite end of the valve. Thus, after selectivelyapplying RF energy to one side of the vein wall, the catheter can beturned 180 degrees around to apply energy to the other side of the veinwall, so as to promote the restoration of the function of the vein.Alternatively, an asymmetrical balloon as shown in FIG. 12, or anothersuch positioning device, can be used to appose the electrodes againstthe venous section to be treated. The balloon may be deflated and theninflated to allow easier movement and repositioning of the catheter.

After treating one section of the vein, the catheter can be moved to thelevel of the next section of vein to be repaired. The same procedurewould then be repeated for each subsequent instance of vein repair. Thetreatment may be repeated several times until sufficient shrinkage isachieved to restore venous function and valvular competence, while thevein retains patency. After completing the treatment for the incompetentvenous sections, the electrode containing catheter is removed from thevein.

An embodiment of the catheter 10 having electrodes 12 on the working end11 which causes localized heating of the surrounding venous tissue andshrinkage of the vein described, as shown on FIGS. 3 and 5, is shown inmore detail in FIG. 7. The electrodes 12 include two ring electrodes 14and 16. The end ring electrode 14 can act as the active electrode, andthe ring electrode 16 can act as the return electrode, or vice versa.The end ring electrode 14 is preferably spaced away from the tip of theworking end of the catheter which may be formed from plastic or someother non-conductive material. The RF field created by the ringelectrodes 14 and 16 should not extend past the end of the catheter. Theinert non-conductive tip of the working end of the catheter helpsprevent shrinkage past the end of the catheter by limiting the extentand formation of the RF field. This non-conductive tip acts as ashrink-limiting mandrel to prevent the veins from shrinkage to adiameter less than the catheter tip and can extend 2 to 25 mm past theelectrode 14. Both electrodes 14 and 16 are preferably made fromstainless steel. An insulator material 18 is located between the endelectrode and the ring electrode. The catheter 10 and electrodes 12should be constructed from materials which would allow visualizationunder fluoroscopy, x-ray, ultrasound, or other imaging techniques. Forexample, the catheter 10 can be configured to deliver x-ray contrastmedium to allow visualization by fluoroscopy. Contrast media injectedinto the vein can be used to assess the condition of the vein and therelationship of the catheter to the treatment area of the vein byphlebography during the shrinkage process.

The catheter 10 includes a stranded, twisted center conductor 20surrounded by a layer of insulation 22 which is preferably formed fromTFE Teflon®. A silver-coated copper braid 24 surrounds the insulatedcenter conductor, and provides flexible and torqueable characteristicsto the catheter shaft. A sheath 26 covers the copper braid 24. Thesheath 26 is preferably made of an electrically resistive, biocompatiblematerial with a low coefficient of friction such as Teflon®. The centerconductor 20 is connected to a power source 34 such as an RF generator,to provide RF energy to the electrodes 12.

While the electrodes 12 have been described as ring electrodes, otherelectrode configurations and arrangements can be used. For example,equidistantly spaced longitudinal electrodes can be used to provideomnidirectional and circumferential shrinkage and to minimize lengthwisecontraction of the vein. The electrodes form an RF fieldcircumferentially around the electrode.

It is to be understood that although a bipolar arrangement is described,a monopolar arrangement may also be used. In a monopolar arrangement, aninside electrode, such as a mesh or wire electrode, is inserted into acavity in a patient's body. An outer electrode having a much largersurface area than the inside electrode is placed on the outer surface ofthe patient's body near the treatment site. For example, an externalmetal plate is placed on the skin over the region to be treated by theinside electrode. The electrodes are connected to a RF generator whichproduces an electric field within the patient's body. Because thesurface area of the inner electrode is much smaller than that of theouter electrode, the density of the electric field is much higher aroundthe inside electrode. The electric field reaches its highest densitybetween the two electrodes in the region near the inside electrode. Theincreased density of the field around the inside electrode allowslocalized heating of the tissues surrounding the inside electrode. Thedegree of heating may be dependent on such factors as the impedance anddielectric constant of the tissue being heated.

The end ring electrode 14 and the ring electrode 16 are preferablylocated between the sensors 30 for measuring values such as impedance.In measuring impedance, as will be described in further detail later,the area between the electrodes often provides the most relevant data.It is to be understood that the sensors 30 may be used to measure othervalues including temperature and ultrasound signals. Further, thepositioning of the sensors 30 on the catheter 10 can vary depending onthe value being measured. For example, when measuring temperature, itmay be desirable to place the sensor on or immediately adjacent to theelectrode. The temperature sensor can sense the temperature of thetissue around the electrodes. When measuring echo signals of pulsedultrasound, the sensors may be placed between the electrodes, or at thetip of the catheter. When measuring pulse echo ultrasound signals, thecatheter is preferably rotated to resolve an image of the environmentsurrounding the catheter and the sensors.

The sensors 30 measure parameters which can be used to determine theextent of vein shrinkage. For example, the sensors 30 can be sensingelectrodes which measure the impedance of the venous tissue in contactbetween the end electrode 14 and the ring electrode 16. A constant RFcurrent is emitted from the active end electrode 14 to the return ringelectrode 16. Also, the impedance may be measured between the electrodes14 and 16 directly. The voltage across the electrodes is measured by thesensing electrodes to detect the impedance of the volume between theelectrodes. The voltage measured is proportional to the impedance Zbetween the electrodes, where Z=V/I and the current, I, is constant. Theimpedance changes as a function of the diameter of the vein becausethere is less blood and less conductance as the venous diameterdecreases. As the volume decreases due to shrinkage, the amount ofconductive volume between the electrodes decreases, and the increasedimpedance causes a corresponding increase in the measured voltage. Thistechnique allows for the measurement of vein shrinkage in relativeterms. The signals from the sensing electrodes can be input to amonitor, or microprocessor 32 which could send control signals to the RFgenerator 34 in order to control the application of RF energy to theelectrodes in accordance with the relative impedance measured.Alternatively, the signals from the sensing electrodes can be displayedvisually on a monitor in order to allow for manual control by thephysician.

In an alternate embodiment, the sensors 30 can instead be temperaturesensors such as thermistors. The temperature sensors may be included onthe catheter near the electrodes on the working end to monitor thetemperature surrounding the electrodes and the venous section beingtreated. Application of RF energy from the electrodes may be halted whenthe monitored temperature reaches or exceeds the specific temperature atwhich venous tissue begins to shrink. The signals from the temperaturesensors can be input to the microprocessor 32 for controlling theapplication of RF energy to the electrodes in accordance with themonitored temperature.

Instead of sensing electrodes or thermistors, another embodimentincludes ultrasonic piezoelectric elements which emit pulsed ultrasoundwaves as the sensors 30. The piezoelectric elements are operated in apulse-echo manner to measure the distance to the vein wall from thecatheter shaft. Again, the signals representative of the pulse-echowould be input to the microprocessor 32, or to a monitor to allow formanual control, and the application of RF energy would be controlled inaccordance with the distance computed between the catheter and the veinwall.

The working end 11 of the catheter 10, as shown in FIG. 7, is rounded toprovide an atraumatic tip which minimizes any incidental damage as thecatheter is manipulated within the vein. The working end 11 of thecatheter 10 can have an enlarged dimension which limits the amount oflocal vein shrinkage. An enlarged atraumatic tip may be achieved using abulbous shape for the working end 11. Different sized working ends 11and electrodes 12 can be manufactured separately from the catheter 10for later assembly with the shaft of the catheter 10 so that a singlecatheter shaft may be used with working ends having a variety ofdiameters. A working end having a specific size or shape could then beused with the catheter 10 depending on the type of vein being treated.For example, certain larger veins have a diameter of seven to eightmillimeters (mm), while other veins only have a diameter of 2 to 3.5 mm.Alternatively, the working end 11 and the ring electrodes 14 and 16 canbe flush with the shaft of the catheter as shown in FIG. 8. Othermethods, such as monitoring the amount of shrinkage by fluoroscopy, maybe used to determine and control the amount of shrinkage. In otherrespects, the construction of the catheter in FIG. 8 is similar to thatof FIG. 7, as previously discussed.

Another embodiment of the catheter 10 includes an end electrode 14 whichis a cap electrode formed on the tip of the working end 11 of thecatheter 10. As shown in FIG. 9, the end electrode 14 is preferablyfabricated from stainless steel. The end electrode 14 acts as the activeelectrode, and the ring electrode 16 acts as the return electrode. Thecap electrode 14 of the catheter 10 is rounded to provide an atraumatictip so as to minimize any damage to the surrounding venous tissue as thecatheter is manipulated through the vein. The outer diameters (O.D.) ofthe electrodes 14 and 16 in one example size is 7 French or about 2.3mm. Alternatively, the cap electrode and the working end 11 of thecatheter 10 may have an enlarged dimension from the remainder of thecatheter. The electrodes and the working end, as shown in the exemplaryFIG. 9, are substantially flush with the remainder of the catheter. Thebraid sheath 26 covers the silver-coated, copper braid 24 of thecatheter, and the sheath is flush with the outer diameter of the ringelectrode 16. An insulator tube 18 is located between the end electrodeand the ring electrode. At the working end of the catheter, a solderfill 28 is formed between the center conductor 20 and the end electrode14. The center conductor 20 is isolated from the ring electrode 16 byinsulation 22. The end cap electrode of FIG. 9 does not limit shrinkageof the vein adjacent to the tip of the catheter and therefore can allowthe vein to shrink completely if desired.

In another embodiment, an inflatable balloon 40 coaxially placed overthe braided shaft can center the catheter 10 and the electrodes 14 and16 within the vein lumen in order to avoid unintended electrode contactwith the vein lumen which could otherwise result in uneven heating ofportions of the vein lumen. As shown in FIG. 10, the balloon 40 islocated adjacent to the electrode 16 which is closer to the connectingend of the catheter. The balloon 40 is preferably expandable andcompliant, and fabricated from an elastic material such as latex, whichcan provide intermediate diameters. The balloon can be inflated withsaline or other conductive solutions.

As discussed in connection with FIG. 6, it can be desirable to maintainselective apposition between the electrodes and the venous tissue at thetreatment site. An embodiment of the catheter 10, shown in FIGS. 11 a,11 b and 11 c, is capable of being deflected by a shaft deflection wire29. The catheter includes a silver-coated copper shield 24 and an outerlayer of insulation 26. The electrodes 12 can be four circumferentiallyspaced longitudinal electrodes, as previously discussed. FIGS. 11 a and11 c only show two of four longitudinal electrodes. The catheter 10further includes a stiffening jacket 25 formed around the cathetershaft, except for the working end of the catheter. A central hollow wirelumen 27 extends through the length of the catheter. Theshaft-deflection wire 29 has a stiff bend formed near its working end,and is pushed through the wire lumen 27 of the catheter. The end of thewire 29 after the stiff bend which advances through to the tip of theworking end of the catheter is preferably flexible and pliant. Thestiffening jacket 25 prevents the catheter shaft from being deflected bythe shaft deflection wire 29 until the deflection wire reaches theworking end of the catheter. The bend in the deflection wire 29 movesthe working end 11 of the catheter to one side. The electrodes 12 canthen be selectively placed in apposition with the specific venous tissueto be treated. A contrast medium can also be administered to thetreatment site through the lumen 27. Further, a cooling solution orfluid may be delivered to the treatment site through the lumen 27. Sideports 30 for the lumen can be formed at the working end near theelectrodes 12 for delivering the contrast medium and the cooling fluid.Alternatively, the lumen 27 could be closed at the tip of the workingend of the catheter in order to allow an injection of contrast media orcooling solution to be forced out the side ports 30. Closing the lumen27 at the tip further allows the deflection wire 29 to be made morestiff without concern for the stiffer wire extending past the catheter.

Another embodiment uses an asymmetrical balloon 40 to deflect theelectrodes 12 at the working end 11 of the catheter to one side. Theelectrodes 12 are a pair of longitudinal electrodes located on one sideof the catheter. As shown in FIGS. 12 a and 12 b, the balloon 40 islocated on the opposite side of the catheter. When the balloon 40 isinflated, the opposite side of the working end 11 accommodating thelongitudinal electrodes is moved into apposition with the venous tissueto be treated. After treating the dilated venous section, the balloon 40can be deflated, and the catheter removed from the vasculature. Itshould be noted that the other mechanisms for deflecting the working endof the catheter may be used. For example, a bendable actuation wire maybe used on one side of the catheter in order to perform a functionsimilar to that of the asymmetrical balloon. The catheter furtherincludes the jacket 26, the braid 24, and the TFE insulation 22, and issimilar in construction to the previously discussed embodiments.

In another embodiment, as shown in FIG. 13, the catheter 10 includesbowable electrodes 12 in the form of four conductive elongate members.The bowable electrodes 12 are similar to longitudinal electrodes formedalong the circumference of the catheter, but are not fixed to thecatheter. The catheter itself can fit through a suitably sized sheathfor the procedure. For example, a 9 French sheath, which has about a 3mm diameter, may be used. The working end 11 of the catheter includes amovable tip 31 manually controlled by a diameter actuator 33 located atthe connecting end of the catheter. The movable tip 31 is connected tothe diameter actuator 33 by a central wire (not shown) running throughthe catheter. The diameter actuator 33 may be threaded onto theconnecting end of the catheter. Maneuvering the actuator 33 into and outof the connecting end of the catheter causes a corresponding movement inthe movable tip 31 at the working end of the catheter. If the movabletip 31 is pulled toward the connecting end by the diameter actuator 33,then the electrodes 12 are bowed outwardly. The bowable electrodes 12preferably expand out to treat veins up to 8 mm. If the movable tip 31is pushed out by the diameter actuator 33, the bowable electrodes 12 arethen retracted towards the shaft of the catheter. Consistent contact ofthe electrode can be maintained with the vein wall.

The extent of shrinkage can be controlled by the effective diameter ofthe catheter and the electrode combination. The electrodes 12 may bebowed radially outwards as part of the effective diameter of thecatheter so as to come into apposition with the vein wall. As RF energyis applied, the vein begins to shrink down to the effective diameter ofthe catheter. The effective diameter of the catheter is reduced underthe control of the physician to control the amount of shrinkage. As theeffective diameter is decreased, the electrodes continue to maintainapposition with the venous tissue. As before, the extent of veinshrinkage can be monitored by fluoroscopy, or any other suitable method.After shrinking the vein to the desired diameter, the application of RFenergy from the electrodes 12 is ceased. The desired diameter can be thefinal effective diameter of the catheter, as defined by the deflectedelectrodes 12.

The electrodes 12 may be fabricated from spring steel or nitinol so thatthe electrodes 12 would be biased to return to a reduced diameterprofile. Where the entire length of the bowable longitudinal electrodeis conductive, insulation 35 may be provided over the majority of theelectrode surface in order to prevent any unintended heating effects.The ends of the electrodes are insulated from each other to preventcreating variable field densities at the ends, especially as theeffective diameter increases which would create even greater fielddisparities between the ends and the bowed midsection. The insulation 35can bepolyimide or another type of insulating film. Insulation 35provided along the back of the electrodes away from the vein wallfurther prevents heating of the blood flowing in the vein, which shouldalso reduce the likelihood of coagulation. The remaining exposed area ofthe electrode is preferably the area which contacts the vein wall duringapposition. The heating effect is then focused along the vein wall. Theexposed surface area of the electrode should be as great as allowablewhile maintaining a consistent distance between the exposed sections ofthe electrode along the circumference of the effective diameter. Thelarger the exposed surface of the electrodes apposed against the veinwall during shrinkage, the greater the surface area of the vein wallaffected by the electric field generated by the electrodes.

Another embodiment of the catheter 10, as shown in FIG. 14, includesbowable elongate members 32 having one end anchored to the working end11 of the catheter, and the other end slidably connected to the cathetertowards the connecting end. The catheter shown in FIG. 14 is similar tothat shown in FIG. 13, except that instead of having the elongatemembers act as the electrodes themselves, the electrodes 12 are locatedon the elongate members 32. The elongate members 32 preferably include aflat central area 34 for the electrodes 12. The central area 34 remainssubstantially flat as the elongate members 32 are deflected and bowedoutwardly. The substantially flat central area allows for a more uniformcontact with the vein wall. The flat area establishes a larger surfacearea to assure contact between the electrode 12 on the elongate memberand the vein wall. It is to be understood that the flat area 34 need notbe centrally located on the elongate member 32. The flat area should belocated so as to be the first area that contacts the vein wall. Theelongate members 32 shown in FIG. 14 are connected to a sliding sleeve36 formed along the exterior of the catheter shaft. As the electrodes 12are moved radially outwards and inwards, the slidable sleeve 36 is movedtowards and away from the working end.

The balloon 40 can be furnished between the catheter shaft, and theelongate members 32. Manual manipulation of the sliding sleeve is notrequired in this embodiment, and the sleeve need not travel anysubstantial length of the catheter. The balloon 40 is inflated and comesinto contact with the elongate members 32. As the balloon 40 is furtherinflated, the electrodes 12 are moved outwardly in a radial direction asthe elongate members are deflected and bowed by the expanding balloon40. The balloon is preferably inflated using a non-conductive fluid,especially where the elongate members contain the electrodes, or wherethe elongate member itself is conductive so as to act as the electrode.When the proper diameter for the electrodes is reached, the inflation ofthe balloon ceases, and the application of the RF energy begins. Theballoon 40 covers a greater surface area over the venous treatment site,and ensures proper electrode placement relative to the vein wall whilecontrolling the amount of venous shrinkage. More precise control overthe shape and diameter of the balloon can also be possible using thebowable members. As RF energy is applied, the vein begins to shrink downto the effective diameter of the catheter. The effective diameter of thecatheter is reduced under the control of the physician to control theamount of shrinkage. As the effective diameter is decreased, theelectrodes continue to maintain apposition with the venous tissue. Theapplication of RF energy from the electrodes 12 is terminated aftershrinking the vein to the desired diameter, which is the final effectivediameter as defined by the diameter of the balloon 40 and the deflectedelongate members 32. The balloon 40 is then is deflated to a minimalprofile. The elongate members 32 are preferably fabricated from springsteel or nitinol so that the elongate members 32 would be biased toreturn to a reduced diameter profile when the balloon is deflated.

A cross-sectional view of the electrodes 12 of FIG. 14 along lines 15-15is shown in FIG. 15 a. In the four-electrode configuration, a preferredembodiment is to have the electrodes 12 spaced equidistantly apart alongthe circumference of the catheter. The polarity of each electrode ispreferably opposite to the polarity of the immediately adjacentelectrodes. Thus, a uniform RF field would be created along thecircumference of the catheter by the alternating electrodes. In anotherembodiment, as shown in FIG. 15 b, if adjacent electrodes were to bemoved closer together, two effective pairs of active electrodes ofopposite polarity would be formed along the circumference of thecatheter. While an RF field would still be formed along the entirecircumference of the catheter, the RF field would be strongest betweenthe closest adjacent electrodes of opposite polarity. Shrinkage of thevein would be concentrated where the RF field was strongest.

In an alternative embodiment of that discussed in connection with FIG.14, the outer sleeve 36 can extend down the length of the catheter toallow the operator or physician to mechanically control the effectiveelectrode diameter during the application of RF energy, so that aseparate balloon 40 is not required. Moving the slidable sleeve towardthe working end 11 of the catheter causes the electrodes to deflect andradially bow outward to an increased diameter. The outer sleeve 34 canbe moved a preset distance to cause the electrodes to bow outwardly to aknown diameter. Bowing the electrodes outwardly also places theelectrodes in apposition with the venous tissue to be treated. Movingthe sleeve 34 toward the connecting end of the catheter pulls back andflattens the electrodes against the catheter before insertion orwithdrawal from the vein. Moving the sleeve controls the diameter of theelectrode deployment for proper treatment of vein lumen having differentdiameters, and for providing varying degrees of vein shrinkage. Forexample, the electrodes could be placed in contact with the venoustissue, and the effective diameter could be mechanically reduced tocontrol shrinkage while RF energy was being applied.

In another embodiment, instead of an outer sleeve, the ends of theelongate members that would otherwise be attached to the outer sleeveare instead slidably located within longitudinal slots or channelsdisposed along the circumference of the catheter. The ends of thebowable members would slide towards the working end within thesechannels as the members are deflected or bowed outwardly, and retreatback towards the connecting end in order to return to their originalconfiguration.

In another alternate embodiment, the electrodes and the elongate memberscould be replaced by a single wire mesh or braided electrode, preferablywhen applying RF energy in a monopolar configuration. As before, theballoon could radially extend the mesh electrode outward into appositionwith the vein wall. The balloon can also control the amount of veinshrinkage.

An alternative method for changing the effective diameter of thecatheters in FIGS. 13 and 14 is to move the electrodes 12 into directcontact with the vein wall. As the electrodes emit RF energy, the veinwall shrinks and pushes the electrodes inwardly towards the catheter.The vein shrinkage reduces the effective diameter directly, rather thanby the active control of the physician, thereby eliminating the need forconstant fine mechanical adjustments to the effective diameter. Amechanism such as a push rod or fixed-diameter balloon can be includedto prevent further radial contraction of the electrodes at a specificeffective diameter, thereby controlling and limiting the amount of veinshrinkage. This has the advantage of maintaining the electrodes inapposition with the venous tissue so that the tissue is heated more thanthe surrounding blood, without requiring the physician to constantlyadjust the effective diameter of the catheter while applying the RFenergy.

Other devices which are controllably expandable or extendable can beused to limit the shrinkage of the vein to a desired size. For example,mandrels can be advanced out through the sides of the catheter to definea diameter limit for shrinking the venous section. As another example, abowable conductive deflection wire can be located on one side of thecatheter for achieving apposition with the vein wall. Furthermore, eventhe non-expandable catheter shaft and electrode shown in FIG. 7 can beused to limit the amount of vein shrinkage during the procedure. Thevein would merely shrink down to the fixed diameter of the catheter.

Other methods may be used with the catheter for maintaining apposition.For example, a pressure cuff may be used to apply external pressure tothe leg to compress the treatment area so that the vein wall comes intocontact with the electrodes. Apposition of the electrodes with thevenous tissue would be maintained by the applied external pressure. Suchexternal compression may be used when treating the superficial veins.Methods other than the aforementioned mechanical methods may also beused to control the magnitude of vein shrinkage. Such non-mechanicalmethods include controlling the time and temperature of the venous RFtreatment.

The working end of the catheter 10 could be constructed to have a bendnear the working end as shown in FIG. 11 so that the catheter can berotated to create a stirring effect within the vein in order to achievemore uniform heating of the venous tissue for more even shrinkage.Rather than a permanent bend, the catheter can be manufactured toprovide a controllable bend near the working end. For example, the bendmay be formed from a shape-memory metal, manipulatable by a system ofwires, a torquable braid, or a permanent bend in the catheter.

Another method for controlling the heat transfer to achieve more uniformheating is by using an external tourniquet to reduce blood flow orcompress the vein around the catheter at the venous treatment site. Byreducing blood flow either by external compression or an intravenouslyinflated occlusive balloon, the influence of blood flow through thevein, which can carry heat away from the treatment site, is minimized.The heat transfer to the venous tissue during the procedure is lessimpacted by the blood flow, and the shrinkage rate of the vein wouldtherefore be more predictable. Sufficient pressure may also beestablished by the external tourniquet to cause the vein to come intoapposition with the electrodes.

In another embodiment, as shown in FIG. 16, an occlusive centeringballoon 40 is used to retain a static pool of blood near the venoustreatment site. A single occlusive balloon 40 may be used in conjunctionwith the venous valve to retain a pool of blood to be heated, whereinthe electrodes 12 are located between the venous valve and the occlusiveballoon 40. Two occlusive balloons (not shown) may be formed on eitherend of the electrodes to create a static pool of blood at a venoustreatment site away from the venous valve. Such an arrangement isolatesand protects the venous valve when treatment of the valve is notdesired. The occlusive balloons may also be used to center the electrodewithin the vein lumen.

Although not limited to the occlusive balloon embodiment shown in FIG.16, the catheter 10 further includes the electrodes 12 arranged inlongitudinal fashion around the circumference of the catheter. Thisembodiment is similar to the embodiments disclosed and described inconnection with the FIGS. 13 and 14, however, the electrodes in thisinstance are fixed on the catheter and do not bow outwards. This fixeddiameter arrangement allows a RF field to be formed along thecircumference of the catheter. Such an arrangement can provideomnidirectional shrinkage and avoid lengthwise contraction of the vein.The particular positioning and orientation of the longitudinalelectrodes is preferably as shown in FIG. 15 a.

A balloon expandable embodiment, as shown in FIG. 17, includes the fourlongitudinal electrodes 12 arranged in longitudinal fashion around thecircumference of the balloon 40 of the catheter 10. This embodiment issimilar to the embodiments disclosed and described in connection withFIGS. 13 and 14, so as to provide omnidirectional shrinkage and minimizelengthwise contraction of the vein. The particular positioning andorientation of the longitudinal electrodes is preferably equidistant asshown in FIG. 15 a. The catheter 10 as shown in FIG. 17 is anover-the-wire type in which the catheter travels over a guide wire 42through a guidewire lumen 52. The catheter 10 further includes thebraided shield 24 surrounding the guidewire lumen 52. A braid tube 54 isformed around the braid 24. The lumen 56 for the balloon 40, and theballoon tube 55, encircle the braid tube 54. The braid tube forms asealing barrier against the inflation fluid leaking into the guidewirelumen 52 from the balloon lumen. The exterior of the catheter includes aretainer tube 57 holding the conductor leads 20, which connect theelectrodes 12 to an RF generator. A cross-section of the shaft of thecatheter 10 along lines 18-18 of FIG. 17 is shown in FIG. 18.

In another embodiment, the electrodes 12 are located under the balloon40 of the catheter 10. This embodiment, which is shown in FIG. 19 andwhich is similar to that shown in FIGS. 17 and 18, allows for conductiveheating of the venous tissue. The catheter 10 shown in FIG. 19 is anover-the-wire type in which the catheter travels over the previouslyintroduced guide wire 42. The balloon is inflated and expands to comeinto contact with the venous tissue. As discussed previously, theinflated balloon 40 can be used to control or limit the magnitude ofshrinkage of the vein to the outer diameter of the inflated balloon 40.The effective diameter can be controlled by the selective inflation anddeflation of the balloon 40. The inflation medium of the balloon 40 ispreferably a conductive fluid, such as saline solution, so that asignificant amount of the RF energy will still be transferred to thesurrounding venous tissue. However, the inflation medium may absorb acertain amount of the RF energy, which will then be converted to heat.This diffusion of the RF energy could provide greater control over theshrinkage of the vein. Alternatively, a conventional heater coil orcurie point element could be used in place of the electrodes 12 in orderto directly heat the inflation medium, which in turn would conductivelytransfer the heat to the venous tissue.

Another embodiment for controlling the effective diameter as shown inFIG. 20 involves using a central cone-shaped wedge actuator 60 within acentral lumen 62 in the catheter. The electrodes 12 are flexibly mountedto the catheter at the working end. The wedge actuator 60 can be pushedforward to engage the complementary wedges holding the electrodes inorder to increase the effective diameter of the electrode catheter atthe working end. A cross-sectional view taken across lines 21-21 in FIG.20 is shown in FIG. 21. Although the wedge actuator 60 is shown having aconical configuration, it is to be understood that any suitable shapemay be used. For example, the circular cross-sections of a cone could bereplaced by rectangular cross-sections to form a pyramid shape. In anyevent, as the larger diameter sections of the wedge actuator 60 engagethe complementary wedges 64 within the working end of the catheter, theelectrodes 12 are forced radially outward into apposition with thevenous tissue. The tip 65 of the working end of the catheter ispreferably flexible so as to accommodate the expanded diameter of theworking end created by the wedge actuator and complementary wedges. Thetip 65 is also composed of an biologically inert and electricallynon-conductive material so as to prevent shrinkage past the catheter.

As can be readily ascertained from the disclosure herein, the procedureof the present invention is accomplished without the need for prolongedhospitalization or postoperative recovery. The curative restoration ofvenous function is possible without the need for continued lifestylechanges, such as frequent leg elevation, the wearing of relativelyuncomfortable elastic support stockings or prolonged treatment ofrecurrent venous stasis ulcers. Moreover, the need for surgery of thearm and leg for transplantation of arm veins into the leg would not benecessary.

Early treatment of venous disease could prevent more seriouscomplications such as ulceration, thrombophlebitis and thromboembolism.The cost of treatment and complications due to venous disease would besignificantly reduced. There would be no need for extensivehospitalization for this procedure, and the need for subsequenttreatment and hospitalization would also be reduced from what iscurrently needed. Furthermore, the minimally invasive nature of thedisclosed methods would allow the medical practitioner to repair ortreat several venous sections in a single procedure in a relativelyshort period of time.

It is to be understood that the type and dimensions of the catheter andelectrodes may be selected according to the size of the vein to betreated. Although the present invention has been described as treatingvenous insufficiency of the lower limb such as varicose veins in theleg, the present invention may be used to intraluminally treat venousinsufficiency in other areas of the body. For example, hemorrhoids maybe characterized as outpocketed varicose veins in the anal region.Traditional treatments include invasive surgery, elastic ring ligation,and the application of topical ointments. Shrinking the dilated veinsusing RF energy can be accomplished in accordance with the presentinvention. Specifically, the catheter and electrode combination isintroduced into the venous system, into the external iliac vein, theinternal iliac vein, then either the hemorrhoidal or the pudendal vein.The catheter then delivers the electrode to the site of the dilatedhemorrhoidal vein by this transvenous approach. Fluoroscopic techniquesor any other suitable technique such as pulse-echo ultrasound, aspreviously discussed, can be used to properly position the electrode atthe venous treatment site. The treatment site is preferably selected tobe at least two centimeters above the dentate line to minimize pain. Theelectrode applies RF energy at a suitable frequency to minimizedcoagulation for a sufficient amount of time to shrink, stiffen, andfixate the vein, yet maintain venous function or valvular competency.This intraluminal approach avoids the risks and morbidity associatedwith more invasive surgical techniques such as hemorrhoidectomy, whilesignificantly reducing reflux of blood in the area without necrosing orremoving the venous tissue.

Another area of venous insufficiency relates to erectile impotency ofthe penis. A significant number of all physically-induced cases ofimpotence result from excessive drainage of blood from the penile venoussystem. Venous-drainage-impotence can be treated using the presentinvention. Catheters having a sufficiently small diameter can be used todeliver the electrodes through the dorsal vein of the penile venoussystem to shrink this venous outflow path. Fluoroscopic or ultrasoundtechniques can be used to properly position the electrode within theincompetent vein. RF energy or other radiant energy is applied from theelectrodes at a suitable frequency to shrink the surrounding venoustissue in order to reduce the excessive amount of drainage from thepenis while maintaining venous function or valvular competency. Theamount of shrinkage of the vein can be limited by the diameter of thecatheter itself, or the catheter or electrodes themselves can beexpanded to the appropriate size. Ligation of these veins should beavoided so as to allow for the proper drainage of blood from an engorgedpenis which is necessary for proper penile function.

Another area of venous insufficiency suitable for treatment inaccordance with the present invention involves esophageal varices.Varicose veins called esophageal varices can form in the venous systemalong the submucosa of the lower esophagus, and bleeding can occur fromthe swollen veins. Properly sized catheters can be used in accordancewith the present invention to deliver the electrodes to the site ofvenous insufficiency along the esophageal varices. Endovascular accessfor the catheter is preferably provided through the superior mesentericvein or portal vein to shrink the portal vein branches leading to thelower esophagus. Proper positioning of the electrode within the vein canbe confirmed using fluoroscopic or ultrasound techniques. The electrodesapply RF energy or other radiant energy at a suitable frequency toshrink the vein and reduce the swelling and transmission of high portalvenous pressure to the veins surrounding the esophagus while maintainingthe function of the vein. The amount of shrinkage of the vein can belimited by the diameter of the catheter itself, or the catheter orelectrodes themselves can be expanded to a predetermined diameter whichlimits shrinkage of the vein to that diameter.

While several particular forms of the invention have been illustratedand described, it will be apparent that various modifications can bemade without departing from the spirit and scope of the invention.Accordingly, it is not intended that the invention be limited, except asby the appended claims.

1. An apparatus for applying energy to cause shrinkage of a hollowanatomical structure, the apparatus comprising: a catheter having ashaft, an outer diameter and a working end, the outer diameter of thecatheter is less than the inner diameter of the hollow anatomicalstructure; at least two electrodes located at the working end of thecatheter so as to provide effective pairs of electrodes, whereinactivation of the at least two electrodes causes shrinkage of the hollowanatomical structure adjacent to the electrodes; a plurality of bowablemembers located at the working end of the catheter, wherein theshrinkage of the hollow anatomical structure is limited to a diameterdefined by the plurality of bowable members; and a balloon locatedbetween the bowable members and the catheter, and separate from thebowable members, wherein the balloon engages and forces the bowablemembers radially outward when the balloon is inflated.
 2. The apparatusof claim 1, wherein the at least two electrodes comprise a plurality oflongitudinal electrodes arranged along the circumference of the catheterat the working end so as to provide omnidirectional heating along asection of the catheter; wherein the vein is shrunk circumferentiallyand axial shrinking is minimized.
 3. The apparatus of claim 1, furthercomprising a sensor located on the catheter, the sensor providing asignal representative of a condition of the hollow anatomical structure;and a microprocessor receiving the signal from the sensor in order todetermine the amount of shrinkage of the hollow anatomical structurebased on the signals.
 4. The apparatus of claim 1, wherein the catheterincludes a lumen for injecting a contrast medium.
 5. The apparatus ofclaim 1, further comprising at least one impedance measuring sensor formeasuring impedance based on the voltage across the electrodes.
 6. Theapparatus of claim 1, further comprising a microprocessor configured toselect a frequency for the at least two electrodes in order to controlthe spread of the heating effect in the hollow anatomical structure. 7.An apparatus for applying energy to cause shrinkage of a hollowanatomical structure, the apparatus comprising: a catheter having ashaft, an outer diameter and a working end, the outer diameter of thecatheter is less than the inner diameter of the hollow anatomicalstructure; at least two electrodes located at the working end of thecatheter so as to provide effective pairs of electrodes, whereinactivation of the at least two electrodes causes shrinkage of the hollowanatomical structure adjacent to the electrodes; a plurality of bowablemembers located at the working end of the catheter, wherein theshrinkage of the hollow anatomical structure is limited to a diameterdefined by the plurality of bowable members; and a balloon locatedbetween the bowable members and the catheter, the balloon configured toengage and force the bowable members radially outward when the balloonis inflated; wherein the at least two electrodes further include an evennumber of longitudinal electrodes and the longitudinal electrodes arearranged on the catheter so as to provide effective pairs oflongitudinal electrodes.
 8. The apparatus of claim 7, wherein thelongitudinal electrodes are arranged along the circumference of thecatheter at the working end so as to provide omnidirectional heatingalong a section of the catheter.
 9. The apparatus of claim 7, furthercomprising a sensor located on the catheter, the sensor providing asignal representative of a condition of the hollow anatomical structure;and a microprocessor receiving the signal from the sensor in order todetermine when sufficient hollow anatomical structure shrinkage isachieved based on the signals.
 10. The apparatus of claim 7, furthercomprising at least one impedance measuring electrode located on thecatheter between an active electrode and a return electrode, wherein aconstant current is passed between the active electrode and the returnelectrode in order to determine the size of the hollow anatomicalstructure.
 11. The apparatus of claim 7, further comprising amicroprocessor selecting a frequency for the at least two electrodes inorder to control the spread of the heating effect in the hollowanatomical structure.
 12. An apparatus for applying energy to causeshrinkage of a hollow anatomical structure, the apparatus comprising: acatheter having a shaft, an outer diameter and a working end, the outerdiameter of the catheter is less than the inner diameter of the hollowanatomical structure; at least two electrodes located at the working endof the catheter so as to provide effective pairs of electrodes, whereinactivation of the at least two electrodes causes shrinkage of the hollowanatomical structure adjacent to the electrodes; and a plurality ofbowable members located at the working end of the catheter, wherein theshrinkage of the hollow anatomical structure is limited to a diameterdefined by the plurality of bowable members; a balloon is locatedbetween the bowable members and the catheter, wherein the balloonengages and forces the bowable members radially outward when the balloonis inflated; wherein each bowable member has a first end, a second end,and a flat section between the first and second end, wherein the firstend is connected to the catheter, and the flat section contains theuninsulated portion.
 13. The apparatus of claim 12, further comprisingat least one impedance measuring sensor for measuring impedance based onthe voltage across the electrodes.
 14. The apparatus of claim 12,further comprising a microprocessor selecting a frequency for the atleast two electrodes in order to control the spread of the heatingeffect in the hollow anatomical structure.
 15. The apparatus of claim12, wherein the bowable members are generally parallel with the catheterwhen the balloon is not expanded, each bowable member includes one ofthe electrodes, and the electrodes are arranged so as to provideeffective pairs of electrodes.
 16. The apparatus of claim 12, furthercomprising: a sensor located on the catheter, the sensor providing asignal representative of a condition of the hollow anatomical structure;and a microprocessor configured to receive the signal from the sensor inorder to determine, based on the signal, when sufficient hollowanatomical structure shrinkage is achieved.
 17. An apparatus forapplying energy to cause shrinkage of a hollow anatomical structure, theapparatus comprising: a catheter having a shaft, an outer diameter and aworking end, the outer diameter of the catheter is less than the innerdiameter of the hollow anatomical structure; at least one electrodelocated at the working end of the catheter, wherein activation of the atleast one electrode causes shrinkage of the hollow anatomical structureadjacent to the electrode; a plurality of bowable members located at theworking end of the catheter, wherein the shrinkage of the hollowanatomical structure is limited to a diameter defined by the pluralityof bowable members; a balloon located between the bowable members andthe catheter, wherein the balloon engages and forces the bowable membersradially outward when the balloon is inflated; and at least onepiezoelectric element located on the catheter adjacent to the electrodeproducing pulse-echo soundings of the hollow anatomical structure.